Work support shoes for centerless grinding machines

ABSTRACT

Work support shoes for a centerless grinding machine have shank and contact portions. The shank portions are arranged for mounting on the grinding machine and are made of a phenolic base material having a sufficient degree of flexibility to dampen vibrations imparted thereto. The contact portions are secured to and supported by the shank portions to contact and bear against a workpiece being ground and are made of a high density ceramic wear resistant material.

United States Patent [191 Lindsay et a1.

WORK SUPPORT SHOES FOR CENTERLESS GRINDING MACHINES Inventors: Arwin 0.Lindsay, 13445 Oscar St.,

Sylmar, Calif. 91342; Kenneth C. Boalen, 1839A Verdugo Loma Dr.,Glendale, Calif. 91208 Filed: July 26, 1973 Appl. No.: 382,872

US. Cl. 51/238 GG, 51/103 R Int. Cl B24b 5/34, B24b 41/06 Field ofSearch 51/103 R, 103 WH, 103 TF,

References Cited UNITED STATES PATENTS 12/1935 Gertiser 51/103 R 1/1956Ernst 51/238 GG 5/1963 Humes 51/238 S [451 Dec. 17, 1974 3,449,8676/1969 Lindsay 51/103 R FOREIGN PATENTS OR APPLICATIONS 581,618 7/1933Germany 51/103 TF Primary ExaminerDonald G. Kelly AssistantExaminer-Marc R. Davidson Attorney, Agent, or Firm-Huebner & Worrel [57]7 ABSTRACT 5 Claims, 11 Drawing Figures PAIENTH, iii. 1 H914 sum 1 or 2WORK SUPPORT SHOES FOR CENTERLESS GRINDING MACHINES BACKGROUND OF THEINVENTION The present invention relates to work shoes for centerlessgrinding machines. Such work shoes function as guides for holdingworkpieces properly orientated while they are being ground in thegrinding machine.

Heretofore, work shoes have been generally made of carbide tippedsteel.- Unfortunately, such prior art shoes have been found to besubject to the drawbacks of excessive vibration and rapid wear of theircarbide tips. Excessive vibration of the work shoes causes movement ofthe workpieces while they are being ground while excessive wear of thecarbide tips causes gradual displacement of the workpieces from theirproperly orientated positions. Both of these drawbacks or disadvantageslimit the precision of the grinding operation and consequently, theprecision of the parts formed from the workpieces.

SUMMARY OF THE INVENTION Accordingly, it is an object of the presentinvention to provide an improved work shoe for a centerless grindingmachine which is not subject to the aforementioned disadvantages ofprior art work shoes.

It is further an object of the present invention to provide improvedwork shoes as set forth characterized by having shank portions having asufficient degree of flexibility to dampen vibrations imparted theretoby a grinding machine, and contact portions for supporting workpiecesbeing ground made of wear resistant material so as not to be subject toexcessive and/or uneven wear.

In accomplishing these and other objects, there is provided inaccordance with the present invention work shoes for centerless grindingmachines having shank portions and contact portions. The shank portionsare arranged for mounting on the grinding machine and are made ofphenolic base material having a sufficient degree of flexibility todampen vibrations imparted thereto. The contact portions are secured toand supported by the shank portions in position to contact and bearagainst a workpiece being ground, and are made of high density ceramicwear resistant material.

Additional objects of the present invention reside in the specificconstruction of the embodiments of work shoes hereafter shown in thedrawings and described in connection therewith.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of acenterless grinding machine having a pair of work shoes according to thepresent invention mounted therein.

FIG. 2 is a side elevation view of the grinding machine of FIG. 1.

FIG 3 is a perspective view of one of the work shoes of the grindingmachine of FIG. 1.

FIG. 4 is a perspective view of another embodiment of work shoeaccording to the present invention.

FIG. 5 is a perspective view of still another embodiment of work shoeaccording to the present invention.

FIGS. 6a 6c are side elevation views of the work shoe of FIG. 5illustrating different curvatures of its contact surface.

FIG. 7 is a perspective view of yet another embodiment of work shoeaccording to the present invention.

FIG. 8 is a perspective view of a modified form of work shoe of FIG. 7.

FIG. 9 is a perspective view of an additional embodiment of work shoeaccording to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings inmore detail, there is shown in FIGS. 1 and 2 a conventional centerlessgrinding machine generally identified by the numeral 10. The machine 10includes a frame portion 11 having an offset magnet chuck l2 and agrinding wheel 13 mounted in a conventional manner thereon. A protectiveshield 14 is formed around the outboard side of the grinding wheel 13.

An upward projecting plate-like portion 15 is formed as part of thegrinder frame 11. The plate 15 is positioned in alignment with thegrinding wheel 13 and has its edge 16 adjacent the grinding wheel 13shaped so that a workpiece 17 may be positioned thereabove in a properorientation for grinding by 'the wheel 13. The magnetic portion 22 ofthe chuck 12 is positioned to hold the workpiece 17 in this grindingposition.

A partially curved slot 18 is formed in the plate 15 adjacent the edge16. The shape and curvature of the slot 18 conforms with the shape ofthe edge 16. Clamped to the plate 15 by bolts-nut combination 19 toextend therefrom towards the grinding position for the workpiece 17 aretwo shoe support arms 20. The arms 20 have slots 21 of uniform widthformed along the greater portion of their lengths through which thebolts 19 extend. Formed in the outwardly positioned ends 23 of each ofthe arms 20 are holes through which the bolts of bolt-nut combinations24 extend.

Clamped on the upper ends of each of the arms 23 by one of the bolt-nutcombinations 24 are work shoes 30 and 31. The work shoe 30, which ispositioned to the left in FIG. 2, is shown on an enlarged scale in FIG.3.

Referring to FIG. 3, the work shoe 30 has a base or shank portion 32made up of a planar top 33 and a downwardly extending stem 34. Theplanar top 33 is rectangularly shaped and the stem 34 extendsperpendicularly to the upper and lower surfaces of the top 33 across itswidth. The stem 34 is also preferably rectangularly shaped and ispositioned relative to the top 33 so that the top 33 extendssymmetrically to each side thereof. Thereby, the shank 32 defined by thestem 34 and top 33 has a T-shaped cross-section. A hole or opening 35,the axis of which extends substantially parallel to the planar top 33,extends through the stem 34. The hole 35 is dimensioned for receivingthe bolt 24 and is centrally formed in the stem 34 so as to permit thestable mounting of the shank 32 on one of the support arms 20.

The shank 32 defined by the stem 34 and top 33 is formed of a singlepiece of phenolic base material having a sufficient degree offlexibility to dampen vibrations imparted thereto by the grindingmachine 10. A suitable phenolic base material is described and has itsproperties set out in our U.S. Pat. No. 3,449,867, issued l7th June 1969and is a paper based phenolic plastic employing a paper base bonded by aphenol formaldehyde resin of electrical grade. The use of such aphenolic base material for the shank 32 minimizes vibration and chatterof the shank and also minimizes transfer of kinetic energy thereby.

Adhesively secured by a layer of an epoxy resin adhesive 40 on the fiatupper surface of the shank top 33 is the contact portion 41 of the workshoe 30. The contact portion 41 has a flat bottom corresponding in shapeto the upper surface of the shank top 33 and an inwardly curved orconcave top contact surface 42. The contact surface 42 curves along onlyone axis, from its side edge 43 to its side edge 44, to have a curvaturecorresponding to the outer surface of the annular workpiece 17.

The contact portion 41 of the work shoe 30 is made of a single piece ofa suitable high density low porosity wear resistant ceramic material. Asuitable ceramic material is described and has its properties set out inthe above-mentioned US. Pat. No. 3,449,867.

Referring again to FIGS. 1 and 2, the work shoe 31 there shown isidentical to the work shoe 30 with the exception that the stem 34 of itsshank is bent instead of being straight. Thereby, the shoe 31 may bemounted on the right positioned arm 20 with the lower part of the stem34 aligned with the longitudinal axis of the arm 20 and the shoe contactportion 41 facing slightly to the left.

In operation of the grinding machine 10, the annular workpiece 17 may beground or finished in the following manner. The work shoes and 31 aremounted on the upper ends of, the support arms 20 in the manner shown inFIG. 2 and the arms 20 are properly positioned and clamped in place bytightening the bolt-nut combinations 19. The workpiece 17 is positionedin the curved seat defined by the shoes 30 and 31 in contact withmagnetic clutch portion 12. The grinding wheel 13 is then drivencounterclockwise (as viewed in FIG. 2) with the result that theworkpiece 17 rotates in place and its outside periphery is. ground bythe wheel 13.

A modified fonn of work generally identified by the numeral is shown inFIG. 4. The shoe 50 is constructed in a manner similar to theconstruction of the shoe 30 with the following exceptions. lts contactportion is made up of two identically shaped spaced apart support parts51 instaed of one solid piece. The parts 51 each have substantially thesame cross-sectional shape as the contact portion 41 of the shoe 30. Theparts 51 are adhesively secured on opposite ends of the shank top 52parallel to the shank stem portion 53. The portion 54 of the shank top53 which extends between the contact parts 51 is elevated above thesurfaces 55 upon which the parts 51 are mounted so as to providevertical walls 56 which aid in supporting the contact parts 51 on theshank top 52.

FIG. 5 illustrates another embodiment of work shoe which is generallydesignated by the numeral 60. The shoe 60 is constructed like theaforedescribed work shoe 30 with the exception that the shank top 61 isformed as a continuation of the shank stem 62. The shoe contact portion63 is dimensioned to be the same size as the shank top 61 for mountingthereto.

FIGS. 6a 6c are side views of the shoe 60 and illustrate that the shoecontact surface 64 which contacts a workpiece may be made of anycurvature suitable for contacting the specific workpiece to be finished.

FIG. 7 illustrates a work shoe generally identified by the numeral 70.The shoe is constructed like the shoe 60 with the exception that theshank top 71 is concavely shaped and the lower portion of the shoecontact portion 72 has a curvature corresponding to the shank top 71 soas to securely interfit therein.

FIG. 8 illustrates a work shoe generally identified by the numeral 80.The shoe is constructed like the shoe 70 with the exception that theshank top 81 for receiving the shoe contact portion 82 is V-shaped incross-section. The contact portion 82 is shown secured in the \/-shapedtop 81 in a position tilted from the longitudinal plane of the shankstem 83.

FIG. 9 illustrates a work shoe generally designated by the numeralwherein the top 91 of the shoe shank 92 and the contact portion 93adhesively secured thereon are arranged to define a V-shape for cradlinga workpiece.

Throughout the specification and drawings the centerless grindingmachine '10 has been referred to and illustrated for the externalgrinding of a workpiece. However, the machine 10 can also be utilized toaccomplish internal grinding of a workpiece by a rearrangement of thegrinding medium without departing from the spirit of the inventionrelating to the work support shoes.

Although we have herein described our invention in what we haveconceived to be the most practical and preferred embodiment, it isrecognized that departures may be made therefrom within the scope of ourinvention.

We claim:

1. For use in a centerless grinding machine having a grinding wheel, aplate secured to a frame of the machine in general alignment with thecircumferential grinding surface of said wheel and extendingtransversely with respect to the wheel axis, said plate being adapted tobe in alignment with a workpiece to be ground by the wheel, chuck meansto hold the workpiece between said plate and said wheel in the grindingposition, said plate being adapted to extend generally laterally anddownwardly of the workpiece in the grinding position, support armsadjustably mounted on said plate and having inner ends adapted to extendtoward the workpiece in the grinding position, work support shoes havingouter ends adjustably mounted to respective inner ends of said supportarms;

the improvement comprising:

said work shoes each having a workpiece contact portion and a shankportion,

each shank portion having an outer and an inner end,

said outer ends of said shank portions defining the outer ends of saidwork support shoes,

each shank portion being made of a phenolic base material havingsufficient degree of flexibility to dampen vibrations imparted to itsouter end by the grinding machine during the grinding operation wherebyvibration of the inner end is substantially eliminated,

each contact portion being mounted on an inner end of a respective shankportion,

the periphery of the inner end of the shank portion being at leastsubstantially coextensive with the periphery of the contact portion, andeach contact portion having an inwardly facing surface arranged forcontacting and supporting the workpiece,

said contact portion being made of a high density.

low porosity, wear resistant ceramic material.

2. The invention according to claim 1 in which:

6 said contact portion is secured to said shank portion lower end of theT leg and inner end forming the by an epoxy resin adhesive. T crossbar,mvennon accordmg to F 2 Whlch: said contact portion forming an upperportion of the the inner end of the shank portion and the part of the Tcrossbar contact portion secured thereto are shaped to in- 5 terfit 5.The invention according to claim 4 in WhlChI The invention according toclaim 3 in whichZ the shank portions have substantially rectangularsursaid shank portion has a T-shaped cross section, the faces betweenthe inner and Outer endsouter end of the shank portion terminating atthe

1. For use in a centerless grinding machine having a grinding wheel, aplate secured to a frame of the machine in general alignment with thecircumferential grinding surface of said wheel and extendingtransversely with respect to the wheel axis, said plate being adapted tobe in alignment with a workpiece to be ground by the wheel, chuck meansto hold the workpiece between said plate and said wheel in the grindingposition, said plate being adapted to extend generally laterally anddownwardly of the workpiece in the grinding position, support armsadjustably mounted on said plate and having inner ends adapted to extendtoward the workpiece in the grinding position, work support shoes havingouter ends adjustably mounted to respective inner ends of said supportarms; the improvement comprising: said work shoes each having aworkpiece contact portion and a shank portion, each shank portion havingan outer and an inner end, said outer ends of said shank portionsdefining the outer ends of said work support shoes, each shank portionbeing made of a phenolic base material having sufficient degree offlexibility to dampen vibrations imparted to its outer end by thegrinding machine during the grinding operation whereby vibration of theinner end is substantially eliminated, each contact portion beingmounted on an inner end of a respective shank portion, the periphery ofthe inner end of the shank portion being at least substantiallycoextensive with the periphery of the contact portion, and each contactportion having an inwardly facing surface arranged for contacting andsupporting the workpiece, said contact portion being made of a highdensity, low porosity, wear resistant ceramic material.
 2. The inventionaccording to claim 1 in which: said contact portion is secured to saidshank portion by an epoxy resin adhesive.
 3. The invention according toclaim 2 in which: the inner end of the shank portion and the part of thecontact portion secured thereto are shaped to interfit.
 4. The inventionaccording to claim 3 in which: said shank portion has a T-shaped crosssection, the outer end of the shank portion terminating at the lower endof the T leg and inner end forming the T crossbar, said contact portionforming an upper portion of the T crossbar.
 5. The invention accordingto claim 4 in which: the shank portions have substantially rectangularsurfaces between the inner and outer ends.